docs/html/ndk: update sample link to point to github
docs/html/ndk: update sample link to point to github

cherrypick https://googleplex-android-review.git.corp.google.com/#/c/731348

Change-Id: I974704d5d555d1a00c6f22037cb45d49ca3c909d

xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base